Okay, well a few weeks ago my radiator went in my truck while on the highway driven to work. It dumped all the antifreeze all over the engine. Once I got the car back from the mechanic and I fixed the misfiring problem from the antifreeze running down into the boots. I figured I would test to see if the heat still worked. Well it didn't so my first instinct was to change out the thermostat. So I did and still no dice no heat. So, I thinking it may be the heater core or something stuck in the lines. Does any one have any other ideas of what if could be? Thank you.

 

You might have an air bubble in the coolant system, try bleeding it. Though if you've taken in on the highway it should have gone away.

 

check for a set of line clamp pliers on the line lol, i've seen that b4, mechanic simply forgot to remove them, that would be the simplest thing to check... I dont believe theres a shutoff tap on themn though i could be wrong

 

I going to try to bleed the system tonight after work tonight. Thanks.